This study was conducted to test the diagnostic performance of global and segmental T2, native T1 and ECV mapping in a large single-center cohort of patients with clinical acute myocarditis.
Method: Cardiac magnetic resonance (CMR) was prospectively performed in 69 patients with suspected myocarditis (within 5 days of the onset of symptoms and after 3 –month follow up) and 45 controls. Images were acquired on a 1.5 Tesla scanner including T2 mapping (T2 prepared-SSFP) and T1 mapping using a modified look locker inversion recovery sequence ( MOLLI) at, mid level in short axis view. Segmental analysis was performed by tracing a ROI in 6 segments of the myocardium according to the AHA segmentation.
T2 and T1 values were measured before and 15 minutes (for T1 mapping) after contrast administration. LGE images were acquired in short and long axis view. The results are expressed by the median and the 5th and the 95th percentiles.
Results: Patients with myocarditis had significantly higher global T2, native T1 and ECV values: 53ms [51-57] vs 51 [49-53] (p<0.001); 1009 ms [969-1034] vs 963 [946-972] (p<0.001) and 33.8% [32.2-35.4] vs 23 [21.7-25.2] (p<0.001) respectively. The sensitivity, specificity and area under the curve (AUC) for T2 (cutoff 54ms) were 49%, 89% and 0.71 respectively; for native T1 (cutoff 979ms) were 66% and 84% and 0.76 respectively and for ECV (cutoff 28%) were 76%, 100% and 0.84 respectively.
Out of 69 patients, LGE was absent in 11 patients. However, T2, native T1 and ECV values were significantly higher in these 11 patients compared to controls.
Segmental analysis showed that T2, native T1 and ECV mapping were significantly higher in all segments of the left ventricle. However, these 3 parameters do not provide better diagnostic performance than the global analysis.
At 3 month-follow up, T2, native T1 and ECV indexes were significantly lower compared to the acute phase and were not significantly different from the control group
Conclusion: Global ECV provide the best diagnostic performance in adults with suspected acute myocarditis. Segmental analysis of T2, T1 and ECV indexes demonstrated that myocarditis is a diffuse process involving all segments of the myocardium either LGE is present or absent. Further studies are required to confirm these data.